How is the Latin future participle formed?

In Latin, the future participle literally means being about to X or on the point of doing X. It is active, and has the form:amaturus, amatura, amaturumThe best way of spotting the future participle is to look for the -ur- extension (just like English future).It is formed from the supine (4th principal part):amo, amare, amavi, amatum --> amaturus -a -ummoneo, monere, monui, monitum --> moniturus -a -umrego, regere, rexi, rectum --> recturus -a -umaudio, audire, audivi, auditum --> auditurus -a -um